Mechanism for power electrical tap switches



Aug. 10, 1948. MlLLER 2,446,881

MECHANISM FOR POWER ELECTRICAL TAP SWITCHES Filed July 3, 1946 Patented Aug. 10, 1948 IMECHANISM FOR POWER ELECTRICAL TAP SWITCHES Edwin August Miller, Fail-field, Conn.

Application July 3, 1946, Serial No. 681,212

This invention relates to mechanism for power electrical tap switches, and more particularly to tap switches having a single sweep-arm.

The objects of the invention are to provide a quick snap-acting tap switch having no lost motion; to provide a sweep-arm pivotally carrying a rocking member provided with contact and roller elements; to provide a lingering, rubbing contact during a portion of the period in which the roller element is mounting a cam elevation; to provide a greater number of fixed contact points in a given circumference; to provide positive indexing without interference with. contact pressure; and to provide against short circuiting.

With reference to the accompanying drawing, the Figure l is an upright elevation of the improved tap switch partly illustrated in cross-sew tion; Figure 2 is a fragmentary detail illustrating certain parts in a different position than shown in the previous figure; and Figure 3 is a similar detail illustrating said parts in still another different position.

Referring more definitely to the various parts illustrated by the accompanying drawing, the numeral I designates the body of the device in cross-section, 2 the bore extending vertically through the body I, and 3 the shaft positioned within the bore 2, the shaft having fixed shoulders 4 and 5 within the seats 5 and 7, respectively, provided by the body I at opposite ends of the bore 2.

Along radial lines, the top 8 of the body I is provided with fixed individual contact points 9, each point 9 being provided with attaching means in the provision of a terminal l0, Encircling the shaft 3, intermediate its length and spaced away therefrom, is the contact ring ll, an integral portion of its terminal 12.

Formed upon the top 8 of the body I are the individual cam elevations l3 having therebetween. an individual valley 14 being positioned along the radial line of a point 9.

The shaft 3 fixedly carries insulation body member l5 for rotation therewith while, at its lower end the shaft 3 is provided with a knob l6 secured thereto by means of the screw [5A and providing means for the manual operation of the shaft 3 within the bore 2.

Fixedly carried by the insulation body member 15 by the means of the screw I! is a spring member I8 having a portion extending overhead the top 8 of the body I in the provision of a sweep-arm l9, and the lower portion of the spring member l8 providing a contact arm in per- 5 Claims. (Cl. 200-4) 2 manent rubbing engagement with the ring II as the shaft 3 is rotated.

The spring member [3 is provided with a depending block 2| fixed thereto by means of the screw 22. The block 2! may be of insulation material. To the laterally outer end portion of the block 2! is a pivotally depending rocker element 23, preferably of highly conductive copper alloy, carrying at its laterally outer end and facing downwardly a contact 24 of fine silver riveted thereto and thus in position for selective engagement with any one of said points 9.

By the laterally inner end of the rocker element 23 is carried fixedly an inverted U-shaped housing 25 within which is revolvingly mounted a roller element 26 by means of a pin 21 extending through the roller element 26 and the parallel walls of the housing 25, the roller element 26 being thus adapted for selective engagement with any one of the cam elevations l3 or the valleys M.

A conductive jumper element 28 of flexible structure is fixed at one end to the sweep-arm I9 by means of the screw 22 and at the other end to the rocker element 23 by means of the screw 29.

A laterally inner portion of the block 2| serves as a bumper engageable by the upwardly-facing portion of the housing 25.

In operation, upon the manual turning of the knob IS, the sweep-arm I9 is carried by the insulation body member l5 on the shaft 3. Assuming that the roller-element 26 is seated within a valley l4 and the contact 24 is in engagement with the contact point 9 in radial alignment with the valley M, as illustrated by the Figure 2, the shaft 3 may be operated one step in either direction to break the contact 24 engagement with one of the fixed contact points 9 and to make engagement by the contact 24 with an adjoining contact point 9,

The sweep-arm I9 has a spring tension exerted downwardly upon the pivot point 30 of the rocker element 23 and, until the sweep-arm is substane tially lifted by means of the roller element going over a cam elevation, said tension normally maintains engagements by the contact 24 with a fixed contact point 9, and the roller element 26 with a valley l4.

At the initial part of the operation of the shaft 3, the roller element 26 starts to move from its Valley seal? M to mount a cam elevation l3. Because the housing 25 is normally spaced below the block 2| carried by the sweep-arm IS, the roller element 26 must climb an appreciable distance up the cam-elevation I3 before the housing 25 engages the block H to lift the sweep-arm l9 and therefore until then the contact 24 remains in engagement with the fixed contact point 9. In order to lift the contact 24 from off the fixed contact point 9 the roller element 26 must have first reached a certain height in mounting a cam-elevation it that will cause the sweep-arm to be lifted, as explained, and in attaining that height the rocker element 23 is made to tilt upon its pivot 36 thereby maintaining a more firm engagement of the rubbing contact 24 upon the fixed contact point 9 by means of the tension of the sweep-arm l9 thereby delaying, as illustrated by the Figure 3, the breaking of the engagement of the contact 24 with the fixed contact point 9 until the roller element 26 mounts sufliciently toward the summit of the cam-elevation I3 to lift the sweep-arm l9, and hence the contact 24, to be carried to an adjoining fixed contact point 9. Having passed the summit of the cam elevation 13 the roller element 26 jumps with a snap-action to rest within the adjoining valley l4 and with the same snap-action the lifted contact 24 is dropped down into engagement with the adjoining fixed contact point 9.

The employment of the rocker element 3|, it will be noted, reduces to a split moment the time between the break and make movement.

While it is herein described that each valley M is in a radial line with a contact point ii, it is to be noted also that any structure which associates a-particular valley Hi in which the roller element 26 rests while the contact 24 is engaged with a contact point 9 is deemed to be Within the scope of this invention.

I claim:

1. Mechanism for power electrical tap switches comprisin a base; a series of relatively spaced contact points fixedly mounted radially upon said base, said points having attaching means in the provision of separate terminals; a series of relatively spaced cam elevations provided upon said base, said elevations being separated by valleys therebetween in radial alignment with the fixed contact points; a rotatable shaft positioned within a bore centrally provided by said base there through; a conductive ring centrally positioned on said base around said shaft and having an attaching means providing a terminal; an insulation body member fixedly carried by the upper extremity of'said shaft; a conductive sprin member, a lower extremity of said spring being in permanent rubbing contact with said ring, and an upper extremity extending over and fixed to said insulation body member in the provision of a sweep-arm; a block rigidly carried by the extremity of said sweep-arm; a pivotally depending conductive member carried by said block and including a roller element for selective engagements with said elevations and valleys, and a contact for selective engagements with said contact points; a flexible conductive jumper having one end fixed to said sweep-arm and the other end fixed to said pivotally depending member; and a knob with which the lower end of said shaft is provided.

2'. Mechanism for power electrical tap switches comprising a base; a central shaft rotatablyposition'ed within a bore provided by said base; a con ductive sweep-arm carried by one end of said shaft, an extremity of said arm being engaged inpermanent rubbing contact with an integral rin portion of a terminal mounted upon said base, the opposite extremity of said arm being pivotally provided with depending contact and roller elements; a series of fixed relatively spaced contact points positioned in the path of said depending contact element; a series of fixed relatively spaced cam elevations formed on said base in the path of said roller element; and a, knob fixed to the free end of said shaft.

3. Mechanism for power electrical tap switches comprising an insulation base; a central rotatv'ble shaft positioned within a bore provided by said base; a conductive spring sweep-arm carried by the upper end of said shaft; a fixed ring contact mounted upon said base and surrounding said. shaft; a rubbing contact provided by the lower end of said sweep-arm in permanent engagement with said ring; a pivotally depending member carried by the free end of said sweeparm, said depending member including roller and contact elements; a series of fixed relatively spaced contact points positioned upon said base in the path of said depending contact element; a series of fixed relatively spaced cam elevations positioned on said base in the path of said depending roller element; and a knob fixed to the free end of said shaft.

4:. Mechanism for power electrical tap switches comprising a base; a central rotatable shaft positioned within a bore provided by said base; a conductive spring sweep-arm secured to one end of said shaft, an extremity of said arm being en-- gaged in permanent rubbing contact with an i21- tegral ring portion of a. terminal, the opposite extremity of said arm pivotally carrying a depending member having a contact and a roller element mounted within a housing normally spaced below said sweep-arm but movable upwardly to lift the sweep-arm; a series of fixed relatively spaced contact points positioned in the path of the said depending contact element; a series of fixed relatively spaced cam elevations, having a valley therebetween and positioned in the path of said roller element, the tension. of said spring sweep-arm normally maintaining the depending contact and the roller element in engagements with a fixed contact point and with in a valley, respectively, but, with the roller element passing over a cam elevation, the sweep arm, and hence the depending contact, is lifted thereby; and a knob fixed to the free end of said shaft as a means to turn said shaft, and hence the sweep-arm.

5. Mechanism for a power electrical tap switch comprising a base; spaced contact points ar ranged along a circular path upon said base;- spaced cam elevations having valleys therebe-- tween likewise arranged upon said base; a conductivespring weep-arm secured to, and carried by, a rotatable shaft positioned within a bore provided by said base, the free end of said shaft having a knob secured thereto; a pivotally depending conductive member carried by said sweep-arm, said depending member housing a roller element and supporting a contact for engagements with said cam elevations and valleys, and said contact points, respectively; a conductive ring portion of a terminal mounted upon said base, the ring portion being positioned around said shaft, and the lower end of the sweep-arm having a permanent rubbing contact with said ring; whereby, upon manual operation of said shaft one step of the sweep-arm-from one con tact point to the nextthe pivotal member is forced to tilt as the roller element climbs a ca elevation sufliciently to lift said housing up to the weep-arm while the contact remains firmly 5 engaged in rubbing contact with said contact REFERENCES CITED point but lifted therefrom upon the housing The following references are of record in the ing the sweep-arm as the roller element climbs to the summit of the cam elevation, the tension of file of this patent the sweep-arm being released with a snap-action 5 ED STATES PATENTS to engage the cont-act with the next contact point Number Name Date as the roller element slips into a valley. 1,675,683 woofter July 3 1928 EDWIN AUGUST MILLER. 

